The U.S. may not have full diplomatic relations with Cuba, but it does have some prime real estate. In a leafy suburb of Havana stands a magnificent 1942 neo-classical estate that was intended to house the U.S. ambassador to Cuba.

But of course: no embassy, no ambassador. So this pristine 31,750 square feet home is the residence of Jonathan Farrar, the chief of mission at the U.S. Interests Section (an embassy-lite) in Cuba.

On Monday night, New York City’s American Ballet Theatre gathered for a reception in this improbable outpost of grand Federalist style in the capital of Communist country. The ballet company’s visit to Cuba – its first in 50 years — is part of the International Ballet Festival of Havana, which this year is celebrating Alicia Alonso, the Cuban ballerina and founder of the National Ballet of Cuba.

With a run of performances, classes and rehearsals ahead, the mojitos at the reception were for sipping, not chugging. Dancers and guests from political and cultural sectors politely mingled on the terrace. And because the party came at the end of ABT’s first full day in Cuba, talk turned easily to first impressions.

“People talk about how the arts are so embraced here, but to see it has been a delightful surprise,” said ABT’s executive director Rachel Moore.

Tomas van Houtryve for The Wall Street Journal

Eric Tamm, of the American Ballet Theater, jumps for a volleyball in Cuba on Tuesday. Many of the ABT dancers took the morning off to excercise and visit the beach before their rehersal at the Karl Marx theater.

A small contingent of dancers, led by Cuban-born Jose Manuel Carreno, had taken class earlier in the day with other festival participants. “It was in a converted house. It was open-air –- no roof –- and there were old wooden floors,” said dancer Simone Messmer. “I haven’t had that much fun in a ballet class in a while.”

In large part, the fun was in dancing with members of the various companies represented in the festival, including New York City Ballet, the Royal Ballet and the National Ballet of Cuba, the host company.

For soloist Maria Ricetto, the trip is all about soaking up artistic style from other traditions. “The way different people from different cultures approach the art form,” she said.

But before jumping right in Ricetto and the bulk of the company took advantage of the day off to go to Playa del Este, a beach about 90 minutes from Havana. Massages, lunch and jaunts on a catamaran were the order of the day.

ABT principal Ethan Stiefel –- who was just named artistic director of the Royal New Zealand Ballet and will be dancing “Fancy Free” in Havana –- reveled in the island’s lack of telecommunication options. “No computer, no telephone. I was just talking to people,” he said.”I tried not to get sunburned.”

The trip so far was not without challenges. ABT’s flight was delayed, then grounded in Baltimore for five hours due to a fire alarm onboard, which turned out to be from an empty coffee pot that had been left on.

The principal dancer Joaquin de Luz for the New York City Ballet, part of a satellite group that is dancing in the festival, sustained an injury that took him out of the evening’s performances. Without understudies or back-up dancers, some quick edits were made. “We made it work,” said Teresa Reichlen.

At the party, the two ballet companies from New York mixed sociably. The festival’s honoree, Ms. Alonso, could not attend, but guests fluttered with warmth when news spread that Fernando Alonso was seated under the colonnade.

Mr. Alonso, a co-founder of the Cuba company, danced in America with Alicia in the 1930s and helped establish an identifiable Cuban approach to ballet, which has continued to develop here. As Messmer put it after one class: “The Cuban style is all its own.”